


olfactory senses

by helsinkibaby



Category: The Flash (TV 2014)
Genre: Age Difference, F/M, Het, Rare Pair, Romance, Secret Relationship, random meta human doppleganger
Language: English
Status: Completed
Published: 2016-09-23
Updated: 2016-09-23
Packaged: 2018-08-16 22:36:59
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,081
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8120179
Author URL: https://archiveofourown.org/users/helsinkibaby/pseuds/helsinkibaby
Summary: Joe is the only one to realise that Caitlin isn't Caitlin.





	

**Author's Note:**

> Theme: scent  
> Prompt: Any (please no SPN), any/any, Character A is taken and replaced (with idk a robot or a hologram or a pod person?) and Character B instantly knows that not!A is not actually A because the smell is wrong

Joe knows that something is off with Caitlin the second he walks into STAR Labs. She looks up when Barry greets him and ok, since their relationship is hush-hush and top secret, he's not expecting a huge PDA but her eyes slide right off him like he's barely even there. There's no warmth in them, there's no quickly disguised smile that they both hope no-one else noticed. There's no smile at all, and unless there had been literal end of the world stuff going on, Caitlin had always smiled, even before their relationship had changed. 

Joe's confused, quickly runs through every conversation, phone call and text message they've exchanged since he last saw her, dredges his mind for anything that could have upset her and comes up empty. There's always the possibility that Cisco or Barry could have done something, especially unintentionally, that put her into a bad mood but they're carrying on as if things are normal, like there's nothing wrong at all. 

Maybe he's wrong, he tells himself and when Cisco and Barry are across the room in front of the Flash suit, when Caitlin is at her work station frowning at some data, he takes his chance and sidles closer to her, intending to quietly ascertain her plans for later. 

He's a cop and they've hidden what they are for almost six months now - they're good at stealth. 

But stealth goes flying out the window when he's two steps away from Caitlin. 

That's when he stops dead and pulls his gun, has it pointed at her before it even registers that that's what he's doing. 

"Step away from the console." 

It's his best cop's voice and Cisco and Barry whip around, identical expressions of shock on their faces. "Joe, what the hell-" Cisco begins but Joe doesn't blink, doesn't take his eyes off the woman in front of him. 

"Who are you?" he asks. Then, the more important question, "And what have you done with Caitlin?" 

With a whoosh of air Barry is between them, hand outstretched towards Joe. "Look, I don't know-" 

"Bar, that's not Caitlin." He's even more sure of it now, because there's a hard glint to "Caitlin's" eyes that the real Caitlin never had. And when her lips turn up in a cruel smile, it makes Joe's stomach twist because it's just wrong. 

"Very good, Detective." Even her voice sounds wrong and suddenly her face, her body, distorts and shimmers and Barry moves quicker than Joe can see and the next thing he knows, "Caitlin" is down on the ground and then it's not Caitlin, it's a woman he's never seen before. 

"A shapeshifter? Are you kidding me?" Cisco sounds almost indignant at being fooled, while Barry is staring at Joe, jaw slack. 

"How did you know?" 

Joe sidesteps his question neatly. "Cisco, can you do your vibe thing? See if you can see where she was keeping Caitlin."

It's not a question, more of a command but Cisco doesn't quibble, is across the room in an instant, kneeling beside the woman. Minutes later, Barry has the meta human in the pipeline and is back, having detoured to the office in the deepest sub-level where Caitlin had been locked up. He carries Caitlin in his arms, tape still over her mouth, wrists and ankles duct-taped and he deposits her on a bed in the medical bay. Cisco is on hand with a scissors while Barry peels the tape from her mouth, apologising profusely as it pulls at her skin. They listen as she tells her story, apologise some more when it emerges she was bound and gagged down there all day and they never noticed anything amiss. Cisco only turns to Joe once, repeats Barry's earlier question and if he questions Joe's reply - "I'm a cop, Cisco, it's my job" - then he doesn't do it there, and neither does Barry. 

The only one who does question it is Caitlin and she does it later, in the privacy of her apartment when she's finally convinced Cisco she'll be fine alone. They're in her bedroom, tangled in the sheets and each other as the heat of passion and relief cools on their skin, her head resting on his chest when she asks, "So how did you know it wasn't me?" 

In truth, it had taken him a while to realise what had tipped him off, and it had only happened once Barry had brought her back. "She smelled wrong," he tells her and she lifts her head in a hurry, with a frown and a confused laugh. 

"Excuse me?" 

Realising he may have worded that wrong, he amends, "The perfume you like, the one I got you for your birthday. That fancy shampoo you have in the shower. Body wash, fabric conditioner..." He shifts slightly, nuzzling into her neck and inhaling deeply. The scents he'd just described are there, as well as another heavier, muskier scent, one that has no place in STAR Labs, even if they've been tempted occasionally. She shivers in his arms as his lips find her skin, gasps when he finds a particularly sensitive spot and he thinks he's forgiven for his poor choice of words. 

He knows he is when she moves so that she's straddling him, lets her hands slide up his chest. "I may know what you mean," she allows, continuing when he lifts one eyebrow, "Last week, when Barry was in a rush and he spilled half a bottle of your cologne over himself?" The blush starts at her chest, moves up and down simultaneously. "I spent the whole day expecting to turn around and see you there." He grins and the flush on her cheeks darkens still more. "That was the night that I barely let you in the front door..."

Her voice trails off as she rocks against him and his mouth opens slightly as he recalls the evening in question, remembers the shock of his back hitting the wall as she pushed the door closed behind him, remembers the feverish way her lips moved over his as her hands worked on his belt, the look in her eyes as she dropped to her knees...

"Oh really?" His hands find her hips, fingers flexing against her skin before moving up slowly. She arches into his touch. "Tell me more." 

She shakes her head, whimpers as his fingers brush against the curve of her breast. "I don't want to talk..." she whispers and suddenly, neither does he.


End file.
